Liquid level measuring apparatus

ABSTRACT

This invention relates to an apparatus for measuring and recording the changes in magnitude of a variable. The apparatus includes a recording stylus or pencil and a means for carrying a recording medium such as marking paper. The stylus or the means for carrying is connected to a transducer means which follows the changes in magnitude and provides an output to drive the stylus along the width of the paper in one direction when the magnitude is increasing and in the other direction when the magnitude is decreasing. In addition, either the stylus or the means for carrying the paper are connected to rotating means which rotate in one direction only and which are also driven by the output of the transducer. As the rotating means rotates in one direction only, the stylus will produce a straight line along the width of the paper when the output of the transducer is in one direction, and a straight line at an angle to the first line, when the output of the transducer is in the opposite direction. The transducer output direction, of course, reflects an increase or decrease, respectively, in the magnitude of the variable.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part application of applicationSer. No. 692,379, filed June 3, 1976, now U.S. Pat. No. 4,036,055.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to measuring and recording apparatus. Morespecifically, this invention relates to such apparatus which include arecord inscribing means and a record retaining carrying means, one ofsaid means being rotatable relative to the other, the other beingdriveable in two opposed directions, wherein, when the other means isdriven in one direction, the one means rotates, whereas, when the othermeans is driven in the opposing direction, the one means does notrotate.

2. Statement of the Prior Art

It is known to provide instruments which measure and record twodirectional variables. By two directional variables is meant variableswhich experience increases or decreases (up and down) in their intensityor magnitude. Examples of such variables are pressure, temperature,volume, length, light intensity, speed etc.

The above mentioned instrument will have two driving means, one to drivea record inscribing means, such as a pen or stylus, and the other todrive the record retaining carrying means, such as a drum on which apaper or other recording medium is disposed. The means which drives thepen or stylus is actuated by a variable sensing transducer, and theamount and direction in which the pen or stylus is driven is a functionof the magnitude and direction of the variable as sensed by thetransducer. Two separate drives are required as the drive which movesthe record inscribing means must be able to move in two directions, butthe drive which drives the record retaining carrying means must move inone direction only.

In this regard, the prior art provides instruments for measuring andrecording the level of liquid in a container.

It is known in the prior art to provide liquid level and measuringapparatus which use a float arrangement both for the purpose ofdetecting the level of the liquid and for driving a mechanism whicheither indicates or records the liquid level detected. Such apparatusare illustrated in, for example, U.S. Pat. Nos. 87,959, Minor et al,issued Mar. 16, 1869, 872,758, Runyon, issued Dec. 3, 1907, 1,208,026,Smith, issued Dec. 12, 1916, 1,336,090, Schaub, issued Apr. 6, 1920,1,494,034, Stevens, issued May 13, 1924, 2,215,542, Chappel et al,issued Sept. 24, 1940, and 2,496,552, Lewis, issued Feb. 7, 1950 as wellas in British Pat. No. 428,691, Lea, issued May 14, 1935. In all ofthese devices, auxiliary power means and/or clock mechanisms arerequired. This is expensive and the power or clock mechanisms aresubject to breakdown so that there are disadvantages in the use of suchdevices. In addition, most of the devices record at all times that theyare in operation including times when no changes are taking place, i.e.,they are recording redundant information.

STATEMENT OF THE INVENTION

It is an object of the invention to provide measuring and recordingapparatus which overcome the disadvantages of the prior art.

In accordance with the invention, a single means is used to drive boththe record inscribing means and the record retaining carrying means bydriving, respectively, a means movable in two directions and a rotatablemeans. The drive is arranged such that when the means movable in twodirections is moved in one direction, then the rotatable means isrotated, but, when the means movable is moved in the opposite direction,then the rotatable means does not rotate.

In accordance with the invention, apparatus for measuring and recordingincreases and decreases in the magnitude or intensity of a variablecomprises: a record inscribing means and a record retaining carryingmeans, one of said inscribing means or carrying means being adapted tobe rotatably driven relative to said other means, said one meanscomprising rotating means, said rotating means being rotatable in onedirection only; the other means being adapted to be driven linearly intwo directions and comprising linear drive means for driving the othermeans in said two directions; transducer means for measuring saidincreases and decreases and translating said increases and decreasesinto two directional motion corresponding, respectively, with saidincreases and decreases; linking means connecting the output of saidtransducer to said rotating means and to said linear drive means suchthat an output in either direction of said transducer will cause acorresponding motion in either direction of said linear drive means,whereas an output in one direction only of said transducer will causesaid rotating means to rotate in said one direction but an output in theother direction of said transducer will not cause said rotating means torotate; whereby, when said magnitude of said variable changes in oneway, a first straight line will be inserted on said record retainingmeans by the motion of record inscribing means on said record retainingcarrying means; and when said magnitude of said variable is changing inthe other way, a straight line will be inscribed at an angle to said onestraight line on said record retaining carrying means by the motion ofsaid record inscribing means on said record retaining carrying means.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood by an examination of thefollowing description together with the accompanying drawings in which:

FIG. 1 is a front view of one embodiment of the invention;

FIG. 2 is a section through II--II in FIG. 1;

FIG. 3 is a section through III--III of FIG. 1;

FIG. 4 illustrates an exemplary device for providing rotation in onedirection only;

FIG. 5 is an example of the record produced in accordance with theinvention;

FIG. 6 is a perspective view of a second embodiment of the invention;

FIG. 7 illustrates the slotted cylinder and plate arrangement of theFIG. 6 embodiment;

FIG. 8 illustrates the inscribing means arrangement of the FIG. 6embodiment;

FIG. 9 is a perspective view of a further embodiment of the invention;

FIG. 10 is an exploded view of a further embodiment of the invention;

FIG. 11 illustrates some details of the FIG. 9 embodiment; and

FIG. 12 is an example of a record produced with the figure embodiment.

Like numerals represent like parts in all of the figures.

DETAILED DESCRIPTION OF THE DRAWINGS

The principle of the invention is being described below as embodied ininstruments for measuring liquid level in a tank or the like. However,as will be apparent, and as will be discussed below, the same principlecan be used with instruments measuring other variables.

Referring to FIG. 1, A is a frame mounted on a suitable base B. Theframe has spaced apart end brackets 15 and 16 between which is rotatablymounted a reel C provided with a helical groove.

A cord 19 is wound about the groove and has one end connected to a floatmeans 21, the other end to a tensioning weight 23.

Rotatably mounted between the brackets 15 and 16, parallel to the reelC, is a shaft 25 concentric with a recording cylinder 27. The reel shaft17 has on its end a spur gear 28 which meshes with a larger spur gear 29on the end of the shaft 25 so that the shaft 25 is rotated whenever theshaft 17 is rotated. This can be more clearly seen in FIG. 2. Thecylinder 27 is connected to the shaft 25 in such a way that when theshaft 25 rotates in one direction, the cylinder 27 is rotated with it,but when the shaft 25 rotates in the opposite direction, the cylinder 27remains stationary. This is accomplished by a rotating means rotatablein one direction only such as a one-way clutch of suitable knownconstruction between the cylinder 27 and the shaft 25.

As can be seen in FIGS. 1 and 3, a runner D is held in contact with thereel C and has keying parts 33a and 33b extending into grooves of reelC. A bridge 19 extends between the brackets 15 and 16 and the runner ismounted to slide along the bridge 19. By this construction when the reelC rotates the runner D is moved in the axial direction of the reel inone direction or the other. The runner D has a record inscribing meanssuch as a marking stylus 35 projecting from it into contact with arecord retaining means, such as mark sensitive paper 38 to trace a lineon the paper corresponding to the relative movement between the stylusand the paper. The cylinder 27 moves the paper 38 by engagement of achain of perforations at each edge of the paper with a ring ofprojections 37 at each edge of the cylinder 27.

Respective guide eyes 39 and 41 are provided on the runner to guide thecord 19. The cord operates through an opening in the base B.

A scale 49 can be provided adjacent the upper end of the stylus 35, andthe position of the stylus along the scale will indicate the liquidlevel of the tank or other liquid container. As will be obvious, theinventive apparatus is preferably mounted on or above the tank, andopening 48 in base B will communicate with a like opening in the tank,and the floats and cord will pass through both openings so that thefloat 21 and weight 23 are both in communication with the liquid. Thefloat 21 will, of course, follow the level and changes in the level ofthe liquid.

In the arrangement shown in FIG. 1, the cylinder 27 will rotate with theshaft 25 only when the shaft is rotating in a clockwise direction. Itwill remain stationary when the shaft 25 is rotating in acounter-clockwise direction.

In operation, the arrangement shown in FIG. 1 works as follows: Assumingthe tank is full, the stylus 35 will be at the extreme left hand end ofthe scale 49 and the cord 19 will be in the groove at the left hand endof the reel C. As the tank begins to empty, the float 21 will follow thechanging level of the liquid so that the reel C is rotated in acounter-clockwise direction. Because of the engagement between the gears28 and 29, shaft 25 will rotate in a clockwise direction so that thecylinder 27 will rotate with the shaft 25. At the same time, because ofthe engagement between the keying parts 33a and 33b with the grooves ofthe reel, the runner D will move along the bridge 19 to the right handside of the scale 49. The line produced by the stylus on the paperduring this motion is shown in FIG. 5. As can be seen, the emptying lineis at an angle to the filling line which will be discussed below. Thecondition of the tank, having regard to the liquid level therein, is, atall times, indicated by the position of the stylus 35 on the scale 49.

When the tank is being filled again, the float 21 will rise with thechanging liquid level, and this action combined with the action of thetensioning weight 23 will cause the reel C to rotate in a clockwisedirection. The shaft 25 will now be rotated in a counter-clockwisedirection, so that the cylinder 27 will not rotate with the shaft 25.However, the stylus 35, by the action of the keyed parts 33a and 33b,will be moved from right to left along the bridge 19. Thus, during thismotion, the stylus will produce the filling line as shown in FIG. 5. Thefilling line is parallel to the width direction of the paper 38.

A means for insuring that the cylinder 27 rotates in one direction onlywith the shaft 25 is shown in FIG. 4. It will be appreciated that thisis only a schematic illustration, and that many other means, well knownin the art, could be used for the same purpose.

The device in FIG. 4 comprises a slip-clutch like arrangement comprisinga plurality of arms 47 fixedly mounted on the shaft 25 for rotationtherewith. Pivotally mounted on the inside surface 27a of cylinder 27 isa protrusion 49. The protrusion is pivotted on point 51 and is springbiased to urge the right hand edge of the protrusion against the surface27a. When the shaft 25 rotates in the clockwise direction, an arm 47will holdingly engage the protrusion 49 and rotate the cylinder 27 withit. When the shaft 25 rotates in a counter-clockwise direction, theprotrusion 51 will slip over the arms 47 so that the cylinder will notrotate with the shaft 25.

A second, preferred, embodiment of the invention is shown in FIG. 6. InFIG. 6, a float 101 is mounted on a movable arm 103 which is pivotable,relative to fixed arm 107, about pivot point 105. A second movable arm109 is disposed to follow the movement of 103 as it pivots about 105.

The arm 109 continues through the centering block 123 and terminates, atthe upper end thereof, (as can be seen in FIG. 8) in an inscribingarrangement 111. The inscribing arrangement comprises a one way rotatingmeans 129 and an inscribing means, such as a pencil or a pressurescribe, 127. The inscribing arrangement is contained in a rigid cylinder115, made of, for example, glass or hard plastic. The rigid cylindercomprises a slantwise slot 117 and a toothed bottom edge 133 (see FIG.7). The toothed bottom edge is mounted on a plate 119 comprising aplurality of ridges 125. The arrangement is enclosed in an opaquecylinder 113 which includes a second centering block 121 for the rigidcylinder 113.

A record retaining means 141, such as mark sensitive paper etc., isdisposed on the inside surface of the opaque cylinder 113.

With the arrangement as shown, rotation of the inscribing means can takeplace only in the clockwise direction. The second embodiment operates asfollows: With the cylinder 113 mounted on top of a liquid containingtank, and the float 101 inserted into the liquid, the float will followthe level of the liquid in the tank. When the level is rising, i.e., thetank is being filled, the float will be rising and thereby forcing thearm 103 to pivot, in a counter-clockwise direction, about the pivotpoint 105. This will force the arm 109 to move in an upward direction,so that the inscribing means 127 moves in an upward direction.

Because of the direction of slant of the slot 117, if the inscribingmeans 127 were to follow this slot as the inscribing means is movingupwardly, it would have to rotate in a counter-clockwise direction.However, the means 129 will prohibit this, so that the means 127 canmove only straight up, and the inscribing means will inscribe avertically straight line on the paper 141. At the same time, theinscribing means will bear upward against the slot 117, so that therigid cylinder 113 will be lifted upward so that the teeth 133 are outof engagement with the ridges 125, as shown in FIG. 7. As can be seen inFIG. 7, the teeth and ridges are so arranged relative to each otherthat, as the cylinder 113 rotates in a counter-clockwise direction, theteeth will slide over the ridges so that rotation of the cylinder 113 inthe counter-clockwise direction is possible. However, with the cylinderlowered so that the teeth 133 engage the ridges 125, rotation of thecylinder 113 in a clockwise direction is prohibited.

When the inscribing means is moving upwardly, it will move the teeth 133out of engagement with the ridges 125. At the same time, as theinscribing means cannot follow the slot 117, the slot 117 must followthe inscribing means, i.e., the rigid cylinder 113 must rotate in acounter-clockwise direction as the slot moves in a counter-clockwisedirection to remain aligned with the inscribing means. When theinscribing means reaches the top of its stroke, it will be disposed atthe top, left hand end of the slot 117.

As the liquid level begins to fall, the float 101 will fall causing thearm 103 to pivot in a clockwise direction about the point 105. This willcause arm 109 to fall and inscribing means 127 to move in a verticallydownward direction. The inscribing means 127 will bear downwardly on theslot 117 forcing the cylinder 113 downwardly so that the teeth 133engage with the ridges 125. Thus, the rotation of the rigid cylinder 113will be somewhat prohibited.

In order for the inscribing means to follow the slot 117 in its downwardstroke, the inscribing means must rotate in a clockwise direction. Thisis, of course, permissible so that, on the downward stroke, the cylinder113 will not move and the inscribing means will move down and to theright along the slant of the slot 117. As will be obvious, a graph ofthe type shown in FIG. 5 will be produced by the action of the FIG. 6embodiment.

Referring now to FIGS. 9 and 10, an alternate double ratchet arrangementis illustrated therein. This arrangement would be connected with thefloat and movable arm arrangement 101-109 as illustrated in FIG. 9. Thearrangement comprises a bottom cylindrical member 201 having a pin 203extending from the outer periphery thereof. The pin 203 engages in theslot 205 of movable member 207, and the movable member 207 is connectedwith the movable arm 109 so that the movable member 207 will moveupwardly when float 101 moves upwardly (i.e., the tank is being filled)and will move downwardly when the float 101 is moving downwardly. Themovable member includes an inscribing means 208 such as a piece of lead.

Disposed on the interior surface of the cylindrical member 201 is aspring leaf-like pawl member 209. The spring leaf-like pawl memberinteracts as will be described below, to provide a ratchet like actionin the arrangement.

The arrangement further consists of a top wheel structure 211 includinga small diameter wheel 213, having a plurality of equally spaced grooves214 on the outer periphery thereof, and a large diameter wheel 215,having a plurality of equally spaced grooves 216 on the outer peripherythereof. Rim 217 is disposed at the top of structure 211, and 201 and211 are disposed to rotate about the axle 219. An inscribable means,such as a paper roll or a pressure sensitive roll, is included on thecylinder 221 which is disposed to fit tightly over the rim 217. Thearrangement is carried in the outer casing 223 which includes a carryingcylinder 224 on whose top surface is disposed a pawl carrier 225 forcarrying leaf spring-like pawl member 226 facing in the same directionas pawl 209. A plastic dome 227 is provided for covering the entirearrangement. Preferably, the plastic dome has a screw thread at thebottom thereof which is adapted to engage with the mating screw threadon the interior surface of the outer casing 223. With the arrangement inits assembled position, groove 229, at the top end of axle 219, extendsover the top of the cylinder 221 as seen in FIG. 9. Clip 231 engages thegroove to keep the arrangement fixed. At the same time, pawl 209 engagesgrooves 214 and pawl 226 engages grooves 216 to provide a doubleratchet.

The relationship as between the grooves 216 and the pawl 226 isillustrated in FIG. 11. As can be seen in FIG. 11, pawl 226 is disposedrelative to the grooves such that, when 215 is rotating in a clockwisedirection, the pawl will slide over the surface 216b and permit rotationof 215 in a clockwise direction. However, when 215 attempts to rotate ina counterclockwise direction, pawl 226 will abut against the surface216a and prevent rotation in the counterclockwise direction. Thus, theinteraction as between pawl 226 and grooves 216 is to produce a ratcheteffect which permits rotation of 215 in a clockwise direction, but whichprevents rotation thereof in a counterclockwise direction.

Although not illustrated, the relationship as between pawl 209 andgrooves 214 is identical to the relationship as between pawl 226 andgrooves 216. Thus, when the wheel 201 rotates in a clockwise direction,the pawl 209 will abut against the surface of the grooves 214 to carry213 with 201. When 201 rotates in a counterclockwise direction, the pawl209 will slide over the surfaces of the grooves 214 so that 213 will notfollow 201 when 201 is moving in a counterclockwise direction.

In operation, the apparatus illustrated in FIG. 9 operates as follows:

When float 101 is being moved upwardly (i.e., the tank is being filled)the movable arm 109 will be forced in a vertically upward direction.This will force the movable member 207 to move in a vertically upwarddirection as well. Pin 203, engaged in the slot 205 of 207, willaccordingly be driven in a clockwise direction (when looking at thearrangement from the top) forcing 201 to move in the same clockwisedirection. Pawl 209, engaging grooves 214, will drive wheel 213, andintegral wheel 211, in the same clockwise direction so that the roll 221will also move in a clockwise direction. The inscribing means 208, whichengages the inscribable surface of the roll 221, will be movingvertically upward as the roll is moving in a clockwise direction.Accordingly, it will produce a marking such as the marking labelled"FILLING" in FIG. 12 hereof. It is noted that 215 can rotate against theaction of 226 when 215 is moving in a clockwise direction as abovedescribed.

When the float 101 is moving in a downward direction (i.e., the tank isbeing emptied) the movable arm 109 will also move in a downwarddirection. Accordingly, the movable member 207 will also move in thesame vertically downward direction. Pin 203, engaged in slot 205, willnow be forced in a counterclockwise direction (when viewing thearrangement from above) carrying the cylinder 201 in the samecounterclockwise direction. The pawl 209 will now slide over the grooves214 so that the wheel 213 would not tend to move with 201 when 201 isrotating in a counterclockwise direction. At the same time, pawl 226will prevent 215 from rotating in a counterclockwise direction, so thatthe structure 211 will remain stationary while the cylinder 201 isrotating in a counterclockwise direction.

At the same time, inscribing means 208 will move vertically downwardagainst stationary roll 221 to produce a marking such as the markinglabelled "EMPTYING" in FIG. 12 thereof.

It will be clear that, by making minor modifications within the spiritof the invention, the directions on the graph could be changed. Thus, ifthe direction of slant of the slot were reversed, and the permissibledirection of rotation of the inscribing means were reversed, and therelationship of the teeth 133 to the ridges 125 were reversed, then thegraph of FIG. 5 would also be reversed. Similar modifications could bemade having regard to the FIG. 1 embodiment.

A non-permanent indication of the tank level can be provided by scaleadjacent the slot 117 as shown in FIG. 8 which includes the markings F(for Full), H (for Half full) and E (for Empty).

In the above described embodiments, the floats can be consideredtransducers which measure the level of liquid in a tank and translateincreases and decreases in level into physical upwards and downwardsmotion respectively. The transducer motion is then linked mechanicallyto the pen (by the helical grooves in the FIG. 1 embodiment and by themovable rods in the FIGS. 6 and 9 embodiments) as well as the drum forrotating the recording medium (by the gear arrangement in the FIG. 1embodiment, by the action of the pencil on the slot 117 in the FIG. 6embodiment, and by the motion of the means 207 in the FIG. 9embodiment). The linkage is so arranged to permit two directionalmovement of the pencil but only one directional rotation of the drumcarrying the recording medium.

As will be obvious, the same principle can be applied no matter what thetransducer, or what the variable being measured may be. Thus, if we havea pressure sensitive transducer, the output of this transducer couldalso constitute physical motion in two directions. (One direction forincreasing, and the other direction for decreasing, pressure). Thismotion can then be applied to, for example, the shaft 17 in FIG. 1 (byway of a gearing arrangement) or the rods 109 in FIGS. 6 and 9respectively.

In similar ways, variations in temperature, light intensity, speed,length, etc. can be measured on transducers whose output wouldconstitute a physical two directional motion. Once again, this motionwould be linked to recording apparatus of the type illustrated in thedrawings herein.

In a specific example, magnitude of current could be measured by havinga moving core piece in a magnetic coil. The movement of the coil wouldindicate the magnitude of the current, and this movement could bemechanically linked to devices as illustrated in the drawings herein.

Although several embodiments have been described in the foregoing, thiswas for the purpose of illustrating, but not limiting, the invention.Various modifications, which will come readily to the mind of oneskilled in the art, are within the scope of the invention as defined inthe appended claims.

We claim:
 1. Apparatus for measuring and recording increases and decreases in the magnitude or intensity of a variable, and comprising:a record inscribing means and a record retaining carrying means, one of said means being adapted to define a substantially linear path of motion in two directions and comprising first drive means for driving said one of said means in said two directions; the other one of said means being adapted to define a path of motion in a direction to intercept the linear path of motion, said other means comprising second drive means operable in one direction only; transducer means for measuring said increases and decreases and translating said increases and decreases into two directional motion corresponding, respectively, with said increases and decreases; linking means connecting the output of said transducer to said second drive means and to said first drive means such that an output in either direction of said transducer will cause a corresponding motion in either direction of said one means, whereas an output in one direction of said transducer will cause said other means to move in said one direction but an output in the other direction of said transducer will not cause said other means to move; whereby, when said magnitude of said variable changes in one way causing an output from said transducer in the other direction thereof, a first substantially straight line will be inscribed on said record retaining means by the motion of one means relative to said other means; and when said magnitude of said variable is changing in the other way causing an output from said transducer in the one direction thereof, a substantially straight line will be inscribed at an angle to said one straight line on said record retaining carrying means by the motion of both said one means and said other means.
 2. Apparatus as defined in claim 1 wherein said first drive means comprises linear drive means and said second drive means comprising rotating means rotatable in one direction only, whereby said other one of said means is adapted to be rotatably driven relative to said one of said means.
 3. Apparatus as defined in claim 2 wherein said linear drive means drives said record inscribing means; andwherein said rotating means drives said record retaining carrying means.
 4. Apparatus as defined in claim 2 wherein said transducer output is connected to a first elongated arm;said first elongated arm being pivotally connected to a second elongated arm; a third elongated arm in engagement with said first elongated arm so as to be moved upwardly when said first elongated arm is pivoted in a counter-clockwise direction and to move downwardly when said first elongated arm is pivoted in a clockwise direction; said second elongated arm being fixedly connected to the bottom of an opaque cylinder; said third elongated arm extending through said bottom of said opaque cylinder and terminating, in the interior of said opaque cylinder, in an inscribing arrangement; said inscribing arrangement comprising said inscribing means; whereby said inscribing means will move up and down as said transducer moves in a first direction and a second direction and clockwise respectively.
 5. An apparatus as defined in claim 4 wherein said record retaining means comprises marking paper disposed on the inside surface of said opaque cylinder;and wherein said inscribing arrangement is enclosed in a rigid cylinder co-axial with said opaque cylinder; said rigid cylinder comprising a slot slanted at an angle to said second elongated arm; said inscribing means extending through said slot to recordingly contact said marking paper; said rotating means being disposed between said third elongated arm and said inscribing means.
 6. An apparatus as defined in claim 5 wherein the bottom end of said rigid cylinder comprises a teethed end;said teethed end being disposed adjacent a plate on the bottom inside surface of said opaque cylinder; the surface of said plate adjacent said teethed end comprising at least one ridge; the teeth and said ridge being so inter-related that, when said inscribing means is moving downwardly and the teeth engage said ridge, said rigid cylinder is non-rotatable; and when said inscribing means is moving upwardly and the teeth are out of engagement with said ridge, said teeth slide over said ridge and said rigid cylinder is rotatable.
 7. An apparatus as defined in claim 4 wherein said inscribing arrangement comprises a movable member connected to said third elongated arm and adapted to move upwardly when said first elongated arm is pivoted in a counterclockwise direction and to move downwardly when said first elongated arm is pivoted in a clockwise direction;a slot in said movable member extending at an angle to said vertically upward and downward directions; a cylindrical member having a pin on the outer periphery thereof, the said pin engaging in said slot, said cylindrical member being rotatably mounted on an axle, whereby said cylindrical member will be rotatably driven when said movable member moves in an upward and downward direction; a wheel structure, being partially disposed in the interior of said cylindrical member, and being rotatably mounted on said axle; said inscribing means further comprising a roll having an inscribable outer surface, said roll being coaxially mounted on said structure for rotation therewith; and double ratchet means connecting said cylinder with said structure to permit rotation of said structure with said cylinder when said cylinder rotates in one direction and to prevent rotation of said structure with said cylinder when said cylinder rotates in the other direction.
 8. An apparatus as defined in claim 7 and comprising an outer casing for carrying said movable member, said cylinder and said wheel structure, said cylinder and said wheel structure being mounted coaxially with said outer casing; andpawl carrying means disposed in said outer casing; said wheel structure comprising a first wheel of a first diameter, said first wheel being disposed within said cylinder, said first wheel comprising a plurality of equally spaced grooves around the periphery thereof; said structure further comprising a second wheel having a diameter greater than the diameter of said first wheel, said second wheel being disposed outside of said cylinder, said second wheel having a plurality of equally spaced grooves around the periphery thereof; first pawl means disposed on said pawl carrying means in said outer casing and facing in a first direction, said first pawl engaging the grooves on the outer periphery of said second wheel; a second pawl means disposed on the inner surface of said cylinder and facing in said first direction, said second pawl means engaging the grooves on the outer periphery of said first wheel; whereby the interaction of said pawl means with their respective grooves will permit rotation of said structure in said one direction and prevent rotation of said structure in the opposite direction. 